A 28-year-old multigravida at 28 weeks gestation with a singleton pregnancy presents with vaginal bleeding and mild lower abdominal pain. Ultrasound confirms a low-lying placenta (placenta previa) with no signs of placental abruption. Fetal heart rate is reassuring. She then develops regular uterine contractions (6 per 10 minutes) and cervical examination shows 2 cm dilation. What is the most appropriate next step?